Should I get back together with her?

My girlfriend of 4.5 years and I decided to break up two nights ago. I asked her to move out. She was not ready for marriage and continued to give me the same story for the past couple of years..."I want to be with you , I dont want to lose you, but I am just not sure your the one, and I wish that I did not feel this way" Now after reality hit her and she started packing her bags, she blurts out , "I will marry you... I think I am making a huge mistake". Breaking up sucks, watching the person you love pack there bags because of her mixed up emotions is extremly tough. My question is , should I stick to my guns and cut it loose for a while, or bring her back into my life? We have been down this road before, where we were on the brink of breaking up and she asked for more time to sort out her. I know this is a silly place to ask this kind of personal question, but I am so TORN and need some guidance.